This letterbox I've never seen 'in real' (so I might be younger than I've always thought I was!). This one is located at the Zaanse Schans and is from 1914, I learned here.
I grew up with the broader, red 'PTT' letterboxes on standards. On this weblog you can see some older and newer Dutch letterboxes, and here more nostalgic ones.
Due to reorganisations of the Dutch mail company, the name of the mail company, as well as the logo's and letterboxes, have changed through the years. So in my childhood I noticed the forementioned PTT letterboxes (see here an older and here a newer 'PTT' logo), and as a grown-up I saw the TPG boxes, then TNT. And since another reorganisation since May 2011 they call it PostNL.
Although they didn't change the letterboxes everywhere, yet.

To an Australian postcrosser who made made extremely happy by sending me a platypus postcard. And on her turn, she loves violins and so.
Above: photo 'Cat and double bass' by Letizia Volpi, 1992. Below: painting 'The old violin' by John Frederick Peto, painted circa 1890.

The receiver also likes postcards of traditional costumes. So I kept the extra sheet to the 'world' stamp, showing traditional costumes of the Netherlands and Suriname, and escpecially there's interesting information about the messages by the Surinam head scarf, the angisa or anyisa.